In vitro and in situ techniques for research on ruminants are currently much in focus. Since they have good correlations with in vivo data, they are feasible alternatives to predict the nutrition rates of feeds and may be applied in equine research on in vivo apparent digestibility. On the other hand, the disadvantage of these methods is due to the fact that fistulated animals are required to obtain the inoculum. Theodorou et al., (1994) developed an extremely promising gas production technique to assess feeds for ruminants, but still require rumen inoculum obtained from operated animals. Faecal microorganisms function similarly to those in the rumen and in the large intestine of equines. The objective this experiment was to compare rumen liquor and equine faeces as inoculum to determine in vitro digestibility of equine feeds.